X-ray beam mutual interference function measurement device and detection method

Abstract

The present invention relates to an X-ray beam mutual interference function measurement device and detection method, which uses a double crystal monochromator to monochromatize incident white light X-rays with a wide spectral bandwidth; uses an X-ray spatial modulator to electrically control spatial modulation of the X-ray wavefront; uses a crystal to filter out the beam that does not meet the Bragg diffraction condition to form a double-slit effect; uses a focusing optical element to form Young's interference fringes on the focal plane, and uses an image detector to collect the intensity distribution of the interference fringes; a data acquisition and processing system controls the synchronization of data acquisition and double-slit scanning, that is, to achieve sequential scanning measurement, and reversely solves the contrast and phase of the interference fringes through the measurement data to provide complete beam coherence information. The problem of rapid dynamic measurement of mutual interference function measurement is solved.

Description

Technical Field

[0001] The invention relates to a measurement technology, and in particular to an X-ray beam mutual interference function measurement device and detection method. Background Art

[0002] With the development of scientific research, the demand for high-throughput X-ray light source devices such as free electron lasers, synchrotron radiation sources and other large scientific facilities has become increasingly strong in recent years. Many experiments require synchrotron accelerators to produce highly coherent X-rays, such as scanning microscopy, interferometry, coherent scattering and phase measurement. However, at the synchrotron, X-rays are transmitted to the experimental station through a set of complex optical devices. Beamline optics may destroy the coherence of the radiation. Although Liouville's theorem states that static optics will not destroy coherence, the phase may be destroyed, so that satisfactory coherent X-rays cannot be obtained for some experiments. In order to explore the basic physical properties of synchrotron X-ray lasers and obtain coherent X-rays that meet the needs, X-ray coherence measurements are very necessary.

[0003] In order to measure the coherence of X-ray beams, D. Paterson et al. [1] fabricated an array of seven Young's slit pairs on a common X-ray transparent substrate. The slits were fabricated by standard contact optical lithography, and then gold was electroformed on a silicon nitride support film. The coherence was then measured using the Young's double-slit experiment. Yogesh Kashyap et al. [2] placed a thin film between the light source and the detector. X-rays passing through the film generated speckles, and the coherence of the light source was analyzed by calculating the contrast of the speckle image.

[0004] [1]Paterson,D.,Allman,BE,McMahon,PJ,Lin,J.,Moldovan,N.,Nugent,KA,...&Mancini,DC(2001).Spatial coherence measurement of X-ray undulatorradiation.Optics Communications, 195(1-4),79-84.[2]Kashyap,Y.,Wang,H.,&Sawhney,K.(2015).Two-dimensional transverse coherence measurement of hard-X-ray beams using near-field speckle.Physical Review A,92(3),033842.

[0005] The common problems with the above methods include:

[0006] (1) The distance between the double slits needs to be moved mechanically, which places high demands on the repeatability and accuracy of the guide rail.

[0007] (2) The amount of measurement data of the mutual interference function is large, and improving the measurement speed is the key.

[0008] (3) High-precision X-ray slits and pinhole devices are difficult to manufacture, especially for hard X-rays, and the manufacturing error affects the contrast of the interference fringes and the final result. Summary of the invention

[0009] In view of the problems existing in measuring the coherence of X-ray beams, an X-ray beam mutual coherence function measurement device and detection method are proposed. Since the double slits are produced by the deformation of a regular lattice through electric heating, the quality of the slits is guaranteed. At the same time, since the position of the electric heating can be automatically controlled, the measurement speed and accuracy are improved.

[0010] The technical solution of the present invention is: an X-ray beam mutual interference function measurement device, which includes a double crystal monochromator, two modulators, a focusing optical element, an image detector and a data acquisition-processing system in sequence. White light is incident on the double crystal monochromator in parallel, and the double crystal monochromator monochromatizes the incident white light X-ray with a wide spectral bandwidth and then emits it. The emitted monochromatic light enters the first modulator with a controllable timing modulation slit. The modulated light emitted by the first modulator enters the second modulator, and the light beam that does not meet the Bragg diffraction condition is filtered out by the second modulator. Then, the light beam enters the focusing optical element for focusing, and Young's double-slit interference fringes are formed on the focal plane. The image detector collects the intensity distribution of the interference fringes and sends them to the data acquisition-processing system. The data acquisition-processing system controls the scanning measurement and processes the collected data to obtain the measurement data.

[0011] Preferably, the first modulator is an X-ray spatial modulator, comprising an upper and lower reflection layer and a substrate. A heating electrode for electrical control is provided between the reflection layer and the substrate. The heating electrode is composed of a resistor band arranged in a parallel array. Each resistor band has electrodes at both ends. The resistor band is energized to heat the corresponding reflection layer area, so that the reflection layer is deformed to form different areas.

[0012] Preferably, the substrate under the reflective layer is made of a material with a high expansion coefficient and a high conductivity coefficient.

[0013] Preferably, the first modulator is an X-ray spatial modulator, which is formed by bonding a plurality of piezoelectric ceramic units arranged in an array to an X-ray reflector, and the voltage applied to the piezoelectric ceramic units is changed in sequence to generate regional deformation of the reflector by utilizing the piezoelectric effect.

[0014] Preferably, the second modulator is a crystal that performs Bragg diffraction on incident light.

[0015] Preferably, the deformation of the region causes a slit to appear in the output light of the first modulator, and the output light at the position of the region deformation enters the crystal at a Bragg diffraction angle and is reflected, thereby forming double-slit interference.

[0016] Preferably, each resistor band or each piezoelectric ceramic unit in the X-ray spatial modulator can achieve regional deformation, modulate the incident light, and cooperate with the crystal to achieve double-slit interference. The X-ray spatial modulator can control multiple modulation units to modulate and form multiple double-slit interferences.

[0017] Preferably, the data acquisition-processing system controls data acquisition and scanning of the double slits synchronously, that is, implements sequential scanning measurement, and inversely resolves the contrast and phase of the interference fringes through the measurement data.

[0018] A method for measuring the mutual interference function of an X-ray beam comprises the following steps:

[0019] 1) Build an X-ray beam mutual interference function measurement device;

[0020] 2) controlling the X-ray spatial modulator in the device of step 1) to select a desired modulation unit to modulate and deform;

[0021] 3) Sequentially scan the X-ray spatial modulator to form several "double slits" with different spacings and measure the interference pattern;

[0022] 4) Combined with the mutual coherence theory, the measured data is processed to obtain the contrast and phase of the interference fringes;

[0023] 5) Scan the double-slit positions spatially to obtain the mutual interference function of all double-slit interferences.

[0024] The beneficial effects of the present invention are: the X-ray beam mutual interference function measurement device and detection method of the present invention, the high-precision slit system forming method, the traditional machining process is difficult to ensure the quality of the mechanical slit used for hard X-rays, the present invention uses high-precision semiconductor technology, combined with the regular lattice arrangement of the crystal, to form a high-precision slit modulation effect; the overall idea is to use an X-ray spatial modulator, combined with Bragg diffraction of the crystal, to achieve X-ray double-slit interferometry, and then obtain the mutual interference function of the light field; a high-quality modulated double slit formation method, and based on wavefront detection to obtain the modulation information of each slit, thereby demodulating the double-slit interference information. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the X-ray beam mutual interference function measuring device of the present invention;

[0026] Figure 2 This is a structural diagram of the first type of X-ray spatial modulator of the present invention;

[0027] Figure 3 A top view of a heating electrode in the first type of X-ray spatial modulator of the present invention;

[0028] Figure 4 This is a schematic diagram of the modulation principle of the first type of X-ray spatial modulator of the present invention;

[0029] Figure 5 This is a schematic diagram of the modulation principle of the second type of X-ray spatial modulator of the present invention. DETAILED DESCRIPTION

[0030] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0031] like Figure 1 The schematic diagram of the structure of the X-ray beam mutual interference function measurement device shown in the figure includes a double crystal monochromator 2, an X-ray spatial modulator 4, a crystal 5, a focusing optical element 7, an image detector 9 and a data acquisition-processing system. White light 1 is incident on the double crystal monochromator 2 in parallel, and the double crystal monochromator 2 monochromatizes the incident white light X-ray with a wide spectral bandwidth and then emits it. The emitted monochromatic light 3 enters the X-ray spatial modulator and is spatially modulated to change the propagation direction. The modulated light emitted by the X-ray spatial modulator 4 enters the crystal 5 to undergo Bragg diffraction, deflects back to the original incident light path direction, and filters out the light beam that does not meet the Bragg diffraction condition, and then enters the focusing optical element 7 to focus, forming Young's double-slit interference fringes on the focal plane. The image detector 9 collects the intensity distribution of the interference fringes and sends them to the data acquisition-processing system, which inversely resolves the contrast and phase of the interference fringes. The data acquisition-processing system includes two parts of functions, one is used to control the synchronization of data acquisition and double-slit scanning, that is, to realize sequential scanning measurement, and the other part is data acquisition, processing, and display, giving complete beam coherence information.

[0032] The data acquisition-processing system can obtain the coherent measurement data at different positions by sequentially changing the positions of the double slits of the X-ray spatial light modulator, and finally obtain the mutual coherence function of the X-ray light field.

[0033] The X-ray spatial modulator is composed of an active deformable mirror. There are two types of active deformable mirrors, such as Figure 2 The first type of X-ray spatial modulator structure shown in FIG. 1 includes two layers, upper and lower reflection layers 20 and a substrate 22, and a heating electrode 21 is used for electrical control in the reflection layer 20 and the substrate 22; Figure 3As shown in the top view of the heating electrode, the heating electrode 21 is composed of a plurality of resistor strips 32 arranged in parallel arrays, and each resistor strip 32 has electrodes 31 at both ends. The resistor strips can be energized to heat the corresponding reflective layer area. Figure 4 As shown in the schematic diagram of the modulation principle of the X-ray spatial modulator, the spatially distributed laser is incident on the reflective layer 20, and the X-ray reflective layer 20 is heated by selecting the resistor band 32 to form deformations in different regions; in order to improve the spatial resolution of thermal deformation, the substrate 22 of the reflective layer 20 should be a material with a high expansion coefficient and a high conductivity coefficient. Figure 5 As shown in the structural diagram of the second type of X-ray spatial modulator, a plurality of piezoelectric ceramic units arranged in an array are bonded to the X-ray reflector, and the voltage loaded on the piezoelectric ceramic units is changed in sequence to generate local deformation of the reflector by utilizing the piezoelectric effect.

[0034] The X-ray beam mutual interference function measurement device realizes the mutual interference function measurement of X-rays based on the double-slit interference experiment. The specific implementation method is: the X-ray spatial modulator 4 is an active deformable reflector, which forms a local deformation at the position where the slit is to be generated, thereby causing the distortion of the outgoing X-ray wavefront; after passing through the crystal 5, the X-rays reflected by the deformed area cannot pass through the crystal 5 for the light at the deformed position incident at the Bragg diffraction angle and reflect, and the light at the non-deformed position does not meet the Bragg diffraction condition and cannot be emitted, thereby simulating double-slit interference. Each resistor band 32 or piezoelectric ceramic unit in the X-ray spatial modulator can realize regional deformation, modulate the incident light, and cooperate with the crystal to realize double-slit interference, so the X-ray spatial modulator can control multiple modulation units to modulate and form multiple double-slit interference.

[0035] Measurement method of mutual interference function:

[0036] A, control the heating electrode or piezoelectric ceramic in the X-ray spatial modulator, select the desired modulation unit to modulate the deformation.

[0037] B, sequentially scan the X-ray spatial modulator to form several "double slits" with different spacings and measure the interference pattern.

[0038] C. Combined with the mutual coherence theory, the measured data is processed to obtain the contrast and phase of the interference fringes.

[0039] D, spatially scan the double-slit positions to obtain the mutual interference function of all double-slit interferences.

[0040] The invention is scientifically and reasonably designed and can generate high-precision double slits in a dynamic space sequence to achieve the measurement of mutual interference function.

[0041] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An X-ray beam mutual interference function measurement device, It is characterized in that It includes a double crystal monochromator, two modulators, a focusing optical element, an image detector and a data acquisition-processing system in sequence. White light is incident on the double crystal monochromator in parallel. The double crystal monochromator monochromatizes the incident white light X-ray with a wide spectral bandwidth and then emits it. The emitted monochromatic light enters the first modulator with a controllable timing modulation slit. The modulated light emitted by the first modulator enters the second modulator. The light beam that does not meet the Bragg diffraction condition is filtered out by the second modulator, and then enters the focusing optical element for focusing, forming Young's double-slit interference fringes on the focal plane. The image detector collects the intensity distribution of the interference fringes and sends them to the data acquisition-processing system. The data acquisition-processing system controls the scanning measurement and processes the collected data to obtain the measurement data. The first modulator is an X-ray spatial modulator, which is composed of an active deformable mirror. The active deformable mirror has two forms of implementation. The first type includes two layers, a reflective layer and a substrate. A heating electrode for electrical control is provided between the reflective layer and the substrate. The heating electrode is composed of a resistor band arranged in an array in parallel. Each resistor band has electrodes at both ends. The resistor band is energized to heat the corresponding reflective layer area, so that the reflective layer is deformed to form different regions. The second type is composed of a plurality of piezoelectric ceramic units arranged in an array and bonded to an X-ray reflector. The voltage loaded on the piezoelectric ceramic unit is changed in sequence, and the piezoelectric effect is used to produce regional deformation of the reflector.

2. The X-ray beam mutual interference function measuring device according to claim 1, It is characterized in that The substrate under the reflective layer is made of a material with high expansion coefficient and high conductivity.

3. The X-ray beam mutual interference function measuring device according to claim 1 or 2, It is characterized in that The second modulator is a crystal and performs Bragg diffraction on the incident light.

4. The X-ray beam mutual interference function measuring device according to claim 3, It is characterized in that The deformation of the region causes a slit to appear in the light emitted from the first modulator. The light emitted from the position of the deformation of the region enters the crystal at a Bragg diffraction angle and is reflected, thereby forming double-slit interference.

5. The X-ray beam mutual interference function measuring device according to claim 4, It is characterized in that Each resistor band or each piezoelectric ceramic unit in the X-ray spatial modulator can achieve regional deformation, modulate the incident light, and cooperate with the crystal to achieve double-slit interference. The X-ray spatial modulator can control multiple modulation units to modulate and form multiple double-slit interferences.

6. The X-ray beam mutual interference function measuring device according to claim 5, It is characterized in that The data acquisition-processing system controls the synchronization of data acquisition and double-slit scanning, that is, realizes sequential scanning measurement, and inversely resolves the contrast and phase of the interference fringes through the measured data.

7. A method for measuring the mutual interference function of X-ray beams, It is characterized in that Specifically, the method comprises the following steps: 1) constructing an X-ray beam mutual interference function measuring device as described in any one of claims 1 to 6; 2) controlling an X-ray spatial modulator in the device of step 1) to select a desired modulation unit to modulate and deform; 3) sequentially scanning the X-ray spatial modulator to form a plurality of "double slits" with different spacings, and measuring interference patterns; 4) processing the measurement data in combination with mutual interference theory to obtain the contrast and phase of the interference fringes; 5) spatially scanning the double slit positions to obtain the mutual interference functions of all double slit interferences.

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